Creating a Table

Basic Syntax

CREATE TABLE [IF NOT EXISTS] [database.]table

(

column_definition_list,

[index_definition_list]

)

[engine_type]

[keys_type]

[table_comment]

[partition_info]

distribution_desc

[rollup_list]

[properties]

[extra_properties]

Use Example

• To create an ordinary table named table1, run the following command:

  CREATE TABLE example_db.table1

  (

  k1 TINYINT,

  k2 DECIMAL(10, 2) DEFAULT "10.5",

  k3 CHAR(10) COMMENT "string column",

  k4 INT NOT NULL DEFAULT "1" COMMENT "int column"

  )

  COMMENT "table comment"

  DISTRIBUTED BY HASH(k1) BUCKETS 32;

• Create a partitioned table named table2.

  Use the event_day column as the partition column and create three partitions: p201706, p201707, and p201708. The values are as follows:

  • p201706: The value range is [Minimum value, 2017-07-01).
  • p201707: The value range is [2017-07-01, 2017-08-01).
  • p201708: The value range is [2017-08-01, 2017-09-01).

  Each partition uses siteid for hash bucketing. The number of buckets is 10.

  The command for creating a table is as follows:

  CREATE TABLE table2

  (

  event_day DATE,

  siteid INT DEFAULT '10',

  citycode SMALLINT,

  username VARCHAR(32) DEFAULT '',

  pv BIGINT SUM DEFAULT '0'

  )

  AGGREGATE KEY(event_day, siteid, citycode, username)

  PARTITION BY RANGE(event_day)

  (

  PARTITION p201706 VALUES LESS THAN ('2017-07-01'),

  PARTITION p201707 VALUES LESS THAN ('2017-08-01'),

  PARTITION p201708 VALUES LESS THAN ('2017-09-01')

  )

  DISTRIBUTED BY HASH(siteid) BUCKETS 10

  PROPERTIES("replication_num" = "1");

  

  • In the preceding table creation settings, replication_num creates single-copy tables. Doris recommends the default three-copy setting to ensure high availability.
  • You can add a rollup table to a table to improve query performance.
  • By default, the Null attribute of a column in a table is true, which affects the query performance.
  • The bucket column must be specified for the Doris table.

• View the table content.
  • SHOW TABLES;

    +----------------------+
    | Tables_in_example_db |
    +----------------------+
    | table1               |
    | table2               |
    +----------------------+
    2 rows in set (0.01 sec)

  • DESC table1;

    +----------+-------------+------+-------+---------+-------+
    | Field    | Type        | Null | Key   | Default | Extra |
    +----------+-------------+------+-------+---------+-------+
    | siteid   | int(11)     | Yes  | true  | 10      |       |
    | citycode | smallint(6) | Yes  | true  | N/A     |       |
    | username | varchar(32) | Yes  | true  |         |       |
    | pv       | bigint(20)  | Yes  | false | 0       | SUM   |
    +----------+-------------+------+-------+---------+-------+
    4 rows in set (0.00 sec)

  • DESC table2;

    +-----------+-------------+------+-------+---------+-------+
    | Field     | Type        | Null | Key   | Default | Extra |
    +-----------+-------------+------+-------+---------+-------+
    | event_day | date        | Yes  | true  | N/A     |       |
    | siteid    | int(11)     | Yes  | true  | 10      |       |
    | citycode  | smallint(6) | Yes  | true  | N/A     |       |
    | username  | varchar(32) | Yes  | true  |         |       |
    | pv        | bigint(20)  | Yes  | false | 0       | SUM   |
    +-----------+-------------+------+-------+---------+-------+
    5 rows in set (0.00 sec)